Kitchen cabinets are constructed primarily from wood-based sheet material such as plywood, medium density fiberboard, commonly referred to as MDF, particleboard or chip core. These sheet materials are generally comprised of sheets of sliced wood veneer laminated together or wood materials ground and then pressed into sheets of a consistent thickness. They are available in various widths and lengths with four foot by eight foot, four foot by ten foot, five foot by eight foot and five foot by ten foot being common standard sizes available in the United States from a variety of sources.
A common method of processing these sheets into cabinet components is to place the entire sheet of material on the worktable of a computer controlled machine called a CNC router, and then cut out the various parts from the sheet. Parts are commonly nested on the sheet to optimize material usage and minimize scrap. The CNC router cuts the parts and performs any required machining operations as directed by a computer program. This approach to manufacturing products from sheet material has become known as “Nested Based Manufacturing”.
A design software program operating on a computer is commonly utilized to generate the computer program required to machine cabinet components from sheet material. The software program generally performs the task of efficiently positioning or nesting the individual components on each sheet of material in the most efficient manner. The accepted method is to design all the cabinets for a particular application, a kitchen for example, and then cut all the parts for all the cabinets as a single job. This job may require multiple sheets of material, each with various parts nested on it. In general, the larger the number of parts nested as a single job, the more efficiently the computer program can position the parts to minimize scrap.
In this positioning effort, the software generally only considers the size and shape of each part, and does not consider the cabinets in the job for which the part is used. As a result, parts for various cabinets are intermingled in the resulting programmed nest. Generally, the design software program will provide a method to print diagrams identifying the individual parts on each sheet of material and will likewise provide a method to print an identifying label for each individual part. Generally, using the printed nest diagrams the appropriate label is placed on each part after machining but before removing them from the nest. It is then necessary to sort these parts into components for each cabinet based on information provided on the label.
Once sorted into individual cabinets, it is necessary to assemble the individual components into the final cabinet case. This can be a difficult and confusing process, especially when assembling more complex cases with internal shelves and partitions.
Generally, an assembly drawing must be created and provided, referring to each of the individual components and their relationship to one another. If a specific sequence for assembling components for a particular case design is required, this information must also be provided.
Using the information provided, the person assembling the cabinet must develop a mental understanding of the assembly process and sequence and must locate and identify each of the parts based on information provided on the part label. This requires substantial time and mental effort, and materially reduced productivity.
A common method of joining cabinet parts together uses a machined joint that has become known as a “blind dado”. In this approach, a tab, commonly referred to as a tenon, fits into a slot, commonly referred to as a dado. Because the joinery stops short of the edges of the parts and is not visible when assembled, it is referred to as a “blind dado” joint. This joint allows the two mating components to be assembled in two orientations, the correct orientation with the tenon on the bottom as shown, or an incorrect orientation with the top part flipped over and the tenon on top. While the correct orientation is apparent for a corner joint, it may not be apparent for internal joints such as shelves or partitions. This often results in cabinets being assembled incorrectly.
Accordingly, it is the principal object of the present invention to provide an improved method of assembling a number of workpieces provided with mating sets of mortises and tenons, to form a structure such as a cabinet and the like, and to provide a structure made by such method. Another object of the invention is to provide such a method in which the proper orientation of a particular workpiece to be joined to another workpiece by means of a mating mortise and tenon connection, is facilitated. A still further object of the invention is to provide a method of indicating a proper sequence of assembly of a number of workpieces configured to be joined together by mating mortise and tenon connections.